Tetrathionates

The oxidation of the thiosulphate ion SjOj to tetrathionate ion, is used to estimate iodine. 

The quantitative conversion of thiosulfate to tetrathionate is unique with iodine. Other oxidant agents tend to carry the oxidation further to sulfate ion or to a mixture of tetrathionate and sulfate ions. Thiosulfate titration of iodine is best performed in neutral or slightly acidic solutions. If strongly acidic solutions must be titrated, air oxidation of the excess of iodide must be prevented by blanketing the solution with an inert gas, such as carbon dioxide or... 

Mild oxidizing agents such as hydrogen peroxide in acid solutions produce tetrathionates and trithionates (17) ... 

Gold thiosulfate complexes of the form Na2[Au(S202)2] 2H20 [19153-98-1] are prepared by addition of gold trichloride to concentrated sodium thiosulfate solution (89). The gold is completely reduced and some thiosulfate is oxidized to tetrathionate. This complex has been used in the treatment of rheumatoid arthritis. 

Barium tetrathionate [82203-66-5] M 361.6. Purified by dissolution in a small volume of water and ppted with EtOH below 5°. After drying the salt was stored in the dark at 0°. 

Thus the quantitative oxidation of 8203 " by I2 to form tetrathionate and iodide is the basis for the iodometric titrations in volumetric analysis... 

Sodium (and potassium) tetrathionate, M2S4O5, can be made by oxidation of thiosulfate by I2 (p. 714) and the free acid liberated (in aqueous solution) by addition of the stoichiometric amount of tartaric acid. 

Tetra-thionsaure, /. tetrathionic acid, -vana-dlnsaure, /. tetravanadic acid. 

Iodine reacts with thiosulfate ion, S 2-, to give iodide ion and the tetrathionate ion, S4062-. 

The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine CIO- is reduced to Cl-. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, Na2S203 I2 is reduced to I-. The sodium thiosulfate is oxidized to sodium tetrathionate, Na2S406. In this analysis, potassium iodide was added in excess to 5.00 ml of bleach d = 1.00 g/cm3). If 25.00 mL of 0.0700 MNa2S203 was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of NaCIO in the bleach ... 

At high ratios of reductant to oxidant, conditions which favour tetrathionate formation at the expense of sulphate, the Cr(Vl) oxidation of thiosulphate follows kinetics ... 

The work with iodide (preceding sub-section) was extended to thiosulphate , and isosbestic points and second-order kinetics were again obtained with the various Pt(IV) complexes (Table 8). Two 8203 ions are consumed per mole of Pt(IV) reduced, suggesting tetrathionate to be the product of oxidation, viz. 

Although the metabolism of tetrathionate has not been established in detail, it presumably takes place via thiosulfate, sulhte, and sulhde. Tetrathionate, which is a component of some media for enrichment of salmonellas, is able to support the anaerobic growth of Salmonella sp. using glycerol or acetate, and S. enterica with ethanolamine or propan-l,2-diol when vitamin Bj2 is available (Price-Carter et al. 2001). 

Price-Carter M, J Tingey, TA Bobik, JR Roth (2001) The alternative electron acceptor tetrathionate supports Bjj-dependent anaerobic growth of Salmonella enterica serovar typhimurium on ethanolamine or 1,2-propandiol. J Bacterial 183 2463-2475. 

Figure 1.121 Sodium tetrathionate reacts with thiols to form reactive sulfenylthiosulfate intermediates. Another sulfhydryl-containing molecule may couple to this active group to create a disulfide linkage.

A final method of forming disulfide crosslinks between toxins and targeting molecules is the use of S-sulfonate formation using sodium sulfite (Na2SC>3) in the presence of sodium tetrathion-ate (Na2S40g). Tetrathionate reacts with sulfhydryls to form sulfenylthiosulfate intermediates (section 1.1.5.2). These derivatives are reactive toward other thiols to create disulfide linkages... 

Parker D.J., and Allison, W.S. (1969) The mechanism of inactivation of glyceraldehyde 3-phosphate dehydrogenase by tetrathionate, o-iodosobenzoate, and iodine monochloride. J. Biol. Chem. 244, 180-189. 

Pihl, A., and Lange, R. (1962) The interaction of oxidized glutathione, cystamine mono-sulfoxide, and tetrathionate with the -SH groups of rabbit muscle D-glyceraldehyde 3-phosphate./. Biol. Chem. 237, 1356-1362. 

Theis, F.V., and Freeland, M.R. (1941) Thrombo-angiids obliterans clinical observations and arterial blood oxygen studies during treatment of the disease with sodium tetrathionate and sodium thiosulfates. Ann. Surg. 113(3), 411-423. 

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